I have an Arris IPC1100P2 connected to a Yamaha YSP 5600. By setting "Audio Output" to "Pass Through" in the "User Setting" menu of the "BUI MAIN MENU", my YSP 5600 has previously reported receiving "Dolby Digital/Dolby Surround" (5.1) over HDMI from the Arris STB. However, this is no longer the case. No matter what settings I choose, the YSP 5600 shows PCM stereo (2.0) being received from the Arris over HDMI.
Interestingly, if I connect the Arris to the YSP 5600 over optical cable, the YSP-5600 again shows "Dolby Digital/Dolby Surround" (5.1).
Does anyone have an idea what has changed, or how I can recover 5.1 sound?
My Arris IPC 1100p2 shows software release APR-4.8 and Build number: 16.15